Renewable rotary bit



June 5, 1934. f 1 B, DE @STA 1 1,961,819

RENEWABLE ROTARY BIT Filed Dec? 15, 1932 Il-'l- 2.9 42 44 40 V 36 y mvENron. aa Jahnedqsa,

32 ATTORNEY Patented June 5, 1934 RENEWABLE ROTARY BIT `lohn B. De Costa Kansas City, Mo. Application December 15, 1932, Serial No. 647,429

4 Claims.

This invention relates to rotary bits of either frusto-conical or cylindrical form employed in drilling deep wells. Heretofore, bits of this character have been made in one piece vwith the result that when a bit became inoperative by the development of a flat place on its peripheral cutting face the entire bit would have to be discarded even though the remainder of the cutting face was in good condition. As bits of this character are expensive it meant quite a loss to have to discard an entire bit on account of a relatively small worn place in its cutting face.

An object of the'present invention is to provide, in a rotary drilling organization, a rotary bit with removable or renewable cutting sections formed of metal adapted to bore through rockor other hard formations. Each cutting section 'has novel means for its retention in a rotary bit member, so that in the event one or more cutting sections become worn to such an extent as to prevent the bit from rotating upon its axis while at work in a Well the bitI may be raised to the surface and theworn sections be replaced with others within a few minutes and thus avoid the delay and expense of providing an entirely new bit.

In order that the invention may be fully understood, reference willjnow be had tothe accompanying drawing, in which: v

Fig. 1 is a side view of a rotary drilling tool equipped with myinvention.

Fig. 2 is inverted plan view of the rotary drilling toolLl Fig. 3 is a side elevation of one of a plurality of brackets with a rotary bit mounted therein, the bit being in cross section.

Fig. 4 is a rear elevation of one of the rotary bits with a number of the cutting sections removed therefrom.

Fig. 5 is an endelevation of the rotary bit with all of the cutting sectioiisremoved therefrom.

Fig. 6 is ay detail perspective view of a retaining memberfffor holding'the cutting sections in position upon the remainder of the bit.

Fig. 7 is a detail of a floating bushing employed in carrying out the invention.

Fig. 8 is a detail perspective view of one of the cutting sections of the bit.

Fig. 9 shows a vertical sectioncf a modified form of my rotary bit.

Referring in detail to-the differentv parts, 2

i designates a rotary drill body comprising a stock 4 having a threaded shank 6 adapted to be screwed into the lower end of an ordinary drill stem, not shown. The stock 4 is reinforced with (Cl. Z-71) 'a plurality of radially disposed ribs 8 which are spaced apart to leave intervening channels 10 through which the bit cuttings may pass While being flushed from the Well. i

The under side of the stock 4 and the ribs 8 60 are provided with radially-disposed dovetail grooves 12 for the reception of corresponding tongues 14 on the upper portion of a plurality of brackets 16 removably held in place by bolts 19. The lower end of the stock 4'is provided 65 with a removable central support 20 equipped at its lower end with a pilot bit 21. The ribs 8 of the stock 4 are equipped with reamers 22 and the brackets 16 are provided at their lower portions with stub shafts 23 for a purpose which 70 will hereinafter appear. The parts thus far described in detail are substantially the same as some of the parts shown in my U. S. Letters Patent for Convertible drilling tools issued July 19, 1932, No. 1,868,348, although it is to be understood that I do not restrict myself to the above constructions as other suitable means may be employed for carrying the rotary bits 24 forming important features of the present invention.

Each bit 24 comprises a rotary member 26 and a 80 plurality of cutting sections 28, which latter have teeth 29 and are removably mounted'upon the former. Obviously different means may be employed for securing the cutting sections 28 in position upon the' rotary member 26. For that 85 purpose I have shown, in thepresent instance, a plurality of dovetail grooves 30 arranged transversely in the circumferential face of the rotary member 26, and corresponding tongues 32 on the cutting sections 28. Thetongues 32 flt snug- 90 ly but removably within the grooves 30, as shown more clearly by Fig. 4. l

As shown more clearly by Fig. 4, each section 28 has shoulders projecting laterally beyond the tongue 32 and so proportioned that the shoulders on one section abut the shoulders of adjacent sections and thus cooperate in completely covering and protecting the circumferential surface of the rotary member 26 from wear'during the drilling operation.

In the frusta-conical form of bit shown by Figs. 1 to 5, inclusive, the cutting sections 28 are held from longitudinal movementV upon the rotary member 26 by an annular cutter 34 and an annular retainingl element 36. The annular 105 cutter 34 may be either formed integral with, or, as shown on Fig. 3, be removably connected to the reduced end of the rotary member 26. The annular retaining-element 36 is countersunk in the large end of the rotary member 26 and the In abutting endsd of the cutting sections 28, and provided with an annular shoulder 38 to provide clearance between said large end and the adjacent portion of the bracket 16.

In order to relieve the stub shaft 23 and the bore of the rotary member 26 of undue wear a floating bushing 40 is interposed between them as shown on Fig. 3. The bushing 40 while fitting snugly within the rotary member 26 and upon the stub shaft 23 is free to rotate independently thereof, and in order to reduce wear between the contacting surfaces said bushing is equipped with a groove 42, Fig. '7, for holding a lubricant, a portion of which is free to iiow to the stub shaft 23 through an aperture 44`communicating with the groove 42 and extending through the wall of the bushing.

From the foregoing description it is apparent that by equipping each rotary bit 24 with the renewable cutting sections 28, any section on becoming worn to such an extent as to prevent rotation or otherwise interfering with the proper operation of the bit can be readily removed and replaced with a new one without necessitating the discarding of the entire bit as heretofore when the rotary bit and its teeth are formed in one piece, and hence with my arrangement the rotary bit can be maintained in an efficient condition at small expense. l

In the modified form of bit disclosed by Fig. 9, the arrangement and construction is substantially the same as that illustrated by Figs. 1 to 5, inclusive, as is evident by corresponding reference numerals with exponents a, the chief difference being that said modified form is of cylindrical instead of frusto-conical formation.

While I have shown two forms of the bit I rel serve all rights to such other forms and modications as properly fall within the spirit and scope of the invention as claimed.

Having thus described my invention, what I claim and desire to secure by Letters Patent, is:

1. A bit of the character described comprising a rotary member having a circumfenertial surface with transverse grooves therein, abutting cutting sections each having a depending tongue removably fitting within a groove, and shoulders projecting laterally beyond said tongue and so proportioned that the shoulders on one section abut the shoulders of adjoining sections and thereby cooperate in covering the circumference of the rotary member.

2. A bit of the character described comprising a rotary member having a conical circumferential surface with transverse grooves equally spaced therein abutting cutting sections each having a depending tongue removably fitting within a groove, and shoulders projecting laterally beyond said tongue and so proportioned that the shoulders on one section abut the shoulders of adjoining sections and thereby cooperate in covering the circumference of the rotary member.

3. A bit of the character described comprising a rotary member having a circumferential surface with transverse grooves therein, abutting cutting sections each having a depending tongue removably fitting within a groove, a plurality of teeth on each section, and shoulders projecting laterally beyond said tongues and so proportioned thatV the shoulders on one section abut the shoulders of adjoining sections and thereby cooperate in covering the circumference of the rotary member.

4. In combination, a drill stock, brackets connected to the lower end of said drill stock, a stub shaft projecting from each bracket, a rotary member mounted upon each stub shaft and provided with transverse circumferential grooves, abutting cutting sections each having a depending tongue removably fitting within a groove, retaining members on one end of the stub shafts overlapping the adjacent ends of the cutting 'sections and provided with shoulders for spacing the rotary members from the adjacent portions of the respective brackets, and removable members on the opposite end of the stub shafts for holding the cutting sections in assembly with the rotary members and holding the latter members upon the stub shafts.

JOHN B. DE COSTA. 

